Sharif Digital Repository

This paper is concerned with tracking state trajectory at remote controller, stability and performance of linear time-invariant noiseless dynamic systems with multiple observations over the packet erasure network subject to random packet dropout and transmission delay that does not necessarily use feedback channel full time. Three cases are considered in this paper: (1) without feedback channel, (2) with feedback channel intermittently and (3) with full time availability of feedback channel. For all three cases, coding strategies that result in reliable tracking of state trajectory at remote controller with asymptotically zero mean absolute estimation error are presented. Asymptotic mean... 

This paper is concerned with the stability of linear time-invariant dynamic systems over the packet erasure channel subject to minimum bit rate constraint when an encoder and a decoder are unaware of the control signal. This assumption results in co-designing the encoder, decoder and controller. The encoder, decoder, controller and conditions relating transmission rate to packet erasure probability and eigenvalues of the system matrix A are presented for almost sure asymptotic stability of linear time-invariant dynamic systems over the packet erasure channel with feedback acknowledgment. When the eigenvalues of the system matrix A are real valued, it is shown that the obtained condition for... 

In this paper a sub-optimal control technique is proposed for a linear Gaussian system with a few distributed interacting sub-systems. Controller of each sub-system has only access to its own measurement and a noisy version of measurement and control vectors of other sub-systems that are communicated through an Additive White Gaussian Noise (AWGN) communication network. The power to be allocated to each transmitter antenna is calculated so that the received signal is the transmitted signal plus additive white Gaussian noise. Under some conditions it is shown that the proposed sub-optimal control technique results in bounded mean square stability. The satisfactory performance of the proposed... 

This paper is concerned with the stability of nonlinear Lipschitz systems subject to bounded process and measurement noises when transmission from sensor to controller is subject to distortion due to quantization. A stabilizing technique and a sufficient condition relating transmission rate to Lipschitz coefficients are presented for almost sure asymptotic bounded stability of nonlinear uncertain Lipschitz systems. In the absence of process and measurement noises, it is shown that the proposed stabilizing technique results in almost sure asymptotic stability. Computer simulations illustrate the satisfactory performance of the proposed technique for almost sure asymptotic bounded stability... 

In this paper, we propose a new packet routing scheme, i.e., a combined digital and analog network coding scheme (DNC-ANC) suitable for multiple unicast scenario. In this respect, we consider a random access WLAN comprised of single and multi-hop unicast sessions. Then we modify the MAC scheme in order to enable ANC. In order to evaluate the effect of the proposed DNC-ANC scheme analytically, we employ an open queueing network and map the details of MAC as well as routing schemes onto its suitable parameters. By writing the corresponding traffic equations and applying the stability condition, we are able to find the maximum stable throughput for the considered scenario. Finally, we will show... 

Exponential backoff is an intrinsic feature of MAC-layer standards of most types of ad hoc networks. It leads to random access channels with memory. In this paper we propose a new network coding-based packet forwarding scheme suitable for multiple unicast scenarios in downlink direction of a wireless network. The wireless nodes as well as the access point attempt to access the channel, based on slotted Aloha with exponential backoff. In the proposed scheme we convert multiple unicast scenario to a combination of several anycast and a multicast scenarios. By proposing an open multiclass queueing network, we are able to derive the maximum stable download throughput of the network. The... 

This paper is concerned with a distributed model predictive control (DMPC) method that is based on a distributed optimisation method with two-level architecture for communication. Feasibility (constraints satisfaction by the approximated solution), convergence and optimality of this distributed optimisation method are mathematically proved. For an automated irrigation channel, the satisfactory performance of the proposed DMPC method in attenuation of the undesired upstream transient error propagation and amplification phenomenon is illustrated and compared with the performance of another DMPC method that exploits a single-level architecture for communication. It is illustrated that the DMPC... 

We show that if a locally compact group G is non-discrete or has an infinite amenable subgroup, then the second dual algebra L1(G) ** does not admit an involution extending the natural involution of L1(G). Thus, for the above classes of groups we answer in the negative a question raised by Duncan and Hosseiniun in 1979. We also find necessary and sufficient conditions for the dual of certain left-introverted subspaces of the space Cb(G) (of bounded continuous functions on G) to admit involutions. We show that the involution problem is related to a multiplier problem. Finally, we show that certain non-trivial quotients of L1(G)** admit involutions  

Zinc hydrosulfite is produced by slurry reaction between sulfur dioxide and zinc powder. This reaction is the first step of sodium hydrosulfite production in zinc powder processing. In this paper through performing a series of experiments, zinc hydrosulfite production rate is obtained as a function of SO2 flow rate, temperature and specific area of zinc powder. In addition, equations for predicting the end-point of the reaction and the decomposition rate of zinc hydrosulfite after that end-point are proposed. Finally, a time dependent flow rate equation is suggested to predict the maximum yield